A Microfluidic Biochip for Rapid Screening of Pesticide Residues Project Summary The overall goal of this SBIR Phase II project is to develop an easy-to-use, low-cost, field-portable, and sensitive device, HerbiScreen", for rapid screening of pesticide residues in water, beverage, and food samples using an exclusively-licensed patented technology. The screening device consists of a photosynthetic organism-based biochip, either disposable or reusable, and a handheld photocurrent detector. Many pesticides, particularly herbicides, can inhibit photosynthesis in a concentration-dependent manner. Hence, the handheld device can be used as a powerful tool for simultaneously screening multiple pesticide residues. The proof of concept has been successfully demonstrated in Phase I. In Phase I, such a biochip was successfully fabricated and applied to detect atrazine, a model pesticide, in synthetic water and food samples. The biochip is significantly superior to the algae growth-based method in terms of detection limit (1 ppb vs. 100 ppb) and detection time (1 min vs. 2 days). The Phase II work will focus on developing commercial prototypes for the biochip and the testing device. The Phase II specific aims are to: 1) Develop a commercial prototype of disposable, self-contained biochip. 2) Optimize and evaluate the prototype biochip and demonstrate that it can detect atrazine, the model pesticide, down to 1 ppb (4.6 nM) within 1 min with a shelf-life of e 6 months when stored at ambient temperature or 4 0C. 3) Develop a commercial prototype of handheld device for rapid screening of pesticide residues using the prototype biochip. 4) Optimize and evaluate the prototype handheld device and demonstrate that it is capable of rapidly screening pesticide residues at a sensitivity level meeting or exceeding the requirements of EPA. Beyond Phase II, we will have our prototype biochips and handheld devices evaluated at our strategic partners'sites and seek AOAC validation and EPA approval upon successful beta-testings. Contamination of water and food by pesticides and the potential hazard to human health remain major concerns of our society. Current pesticide detection methods such as HPLC, GC, and ELISA test kits require sophisticated instruments, skilled personnel, extensive sample pretreatment, and/or expensive bioreagents, and thus are unsuitable for on-site or routine screenings. Part of the challenge that faces the regulatory agencies and industries is to find more cost-effective technologies capable of on-site or on-line screening of low-level pesticide residues. Due to the high sensitivity, low cost, ease-to-use, relatively high specificity (compared to commercial water acute toxicity tests based on bioluminescent bacteria) and relatively broad sensing spectrum (compared to commercial ELSA kits and immuno-strips), the proposed biochip technology will be a commercially viable tool for rapid screening of pesticide residues in a variety of sample matrices. PUBLIC HEALTH RELEVANCE: Pesticides usually possess a high acute toxicity and/or a wide range of biological activities, and thus even a low level of their residues may adversely impact the environment and human health. The development of the proposed biochip technology will allow screening of pesticide residues in domestic and foreign produce and water supplies prior to entry into the supply chain, thereby enhancing the protection and safety of the nation's agriculture and food supply.